That judgement was hard won. Back in 1981, Carew, newly returned from a spell training Sri Lankan special forces, was approached by British intelligence. His mission: to gather information on the fighting potential of the guerrillas, offer some training and bring out examples of captured Soviet weaponry. Political sensitivities meant Americans were unacceptable for the job.

As an ex-member of the SAS, Carew could claim some impressive credentials. The regiment’s total strength is no more a few hundred men, but it can boast a disproportionate role in almost every British postwar conflict from the Falklands to the Persian Gulf War. Typically, its soldiers are used to operating in small parties behind enemy lines. In the gulf, teams were dropped far inside Iraq to knock out enemy missile batteries.

Carew himself had seen covert service in Northern Ireland and fought in Oman, where the regiment was committed to helping in the fight against a full-scale Communist insurgency. But conditions in Afghanistan had a brutality of their own. When he quit the country for the last time almost two years later, he was suffering from hepatitis and a clutch of other complaints that took three months of hospital treatment to cure.

The terrain and the weather demanded extreme endurance. His account of his time with the mujahedin, “Jihad, the Secret War in Afghanistan,” published last year, tells of hiking for days across 15,000-foot mountains, sometimes through waist-deep snow. Meals consisted of no more than rough nan bread and tea. To drink unboiled water was to risk infection. Flexibility was essential. Carew attributes his own success partly to his own background. Growing up on a farm in England, he learnt to make-and change-plans according to the weather rather than the clock.

Always, they faced the threat of attack from an enemy that was vastly better equipped. In the early stages of the war, the mujahedin often depended on ancient bolt-action rifles to combat forces with support from helicopter gunships and tanks. The hit-run-and-hide tactics that served the Afghan tribesmen so well against earlier enemies were no longer so appropriate when any movement could be spotted from the air. What’s more, the Russians, too, were deploying their own special forces, the Spetsnaz. Possibly alone among Western soldiers of the cold war, Carew shot dead a Russian soldier during a firefight in an Afghan village.

As soldiers, the mujahedin had some serious limitations. Tactics were primitive. Discipline and training were rudimentary-although some of their failings were later tackled at British and American-run training camps-and they had little idea of how to maintain their weapons. Alcohol may have been strictly forbidden, but they occasionally smoked opium. According to the demands of their religion, they also stopped regularly to pray. (Carew argues that the Russians made a serious mistake by failing to take account of the religious practices of the conscripted Afghan troops on their own side).

Yet the nature of the country produces a supertough breed of warriors adept at using the terrain to their own advantage, says Carew. “They know the land like a Welsh sheep farmer knows his hillsides.” If crude, their tactics were adapted to their strengths. “They will only attack when they want to. Otherwise you just won’t seem them. They will hide like foxes.” Supplies are buried in dumps across the country, known only to the guerrillas.

A religion that promised paradise to soldiers killed fighting those they saw as infidels provided an extra boost to their courage, according to Carew, that was frequently reckless. And their basic military skills had been honed by the long tradition of intertribal feuding and a ruthless culture of vendetta. Says Carew: “They are very hard and ferocious fighters, although they can also be your best friends.”

That ferocity can show itself as barbarism, especially in the treatment of prisoners. Carew has told of how mujahedin slashed open the stomachs of captured Russians and left them to die in the baking heat. Indeed, the brutality is one reason why Carew is convinced that Afghanistan will be no place for conventional troops. “It will have to be special forces. They have to be used to a Third World way of thinking.”

Besides, the technology of modern warfare may be ill-suited to Afghanistan. Armored vehicles may be bogged down; misty valleys add one more hazard to helicopter flying. Perhaps, says Carew, the answer is to stay out of the country as much as possible and arm the Taliban’s own enemies, the Northern Alliance. On their own territory, it may take Afghans to defeat Afghans.